Mishkat al-Masabih #125

‘Uthman told that when he stood over a grave he would weep so sorely that the tears moistened his beard. Someone said to him, “You remember paradise and hell, without weeping, yet you are weeping over this." He replied that God’s messenger said, “The grave is the first stage of the next world ; if one escapes from it what follows is easier than it, but if one does not escape from it what follows is more severe than it." He further quoted God’s messenger as saying, “I have never seen a sight as horrible as the grave." Tirmidhi and Ibn Majah transmitted it, and Tirmidhi said this is a gharib tradition.